This research aims to study myelinogenesis by further exploring the hypothesis that the murine mutants with disordered formation of myelin have a genetic error in the process of myelin membrane assembly. This thesis which has been developed by determining the short-term rates of biosynthesis of the major proteins and lipids in the CNS of the Quaking mutant and the rates of their incorporation into myelin and other subcellular membranes will be tested by the following: (1) examination of the Shiverer, Jimpy and MDS mutants using similar methods; (2) determination of the turnover of myelin proteins and lipids in these mutants; (3) exploration of aberrant membrane assembly in other site (PNS myelin, spermatid) known to be affected in the Quaking mutant. We also propose a plausible model for the process of myelin assembly which impels us to begin attempts to examine the conditions of translation, insertion, encapsulation and binding of membrane proteins as well as fusion of membrane precursors to the plasmalemma. The mutants will be used as a probe to reveal these steps. The techniques to be employed or developed include isolation of vesicular membrane precursors of myellin, demonstration of myelin preproteins (large precursors), systems for cell-free synthesis of myelin proteins, and detailed analysis of protein primary structure.